From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793717297; b=4gZIKSufSLCP/grrGCycVmkFmT8GiubO+oxZD8UkZHe2XcglKJnyWdIgmbGllcSiDQY2 WlidhFWKAixtp0RSsCDYXWwMFZZYUGIQJchICKaZxe9et3ILogKdcQR2zWqsajJEUhzQQ zXy7Cs8w48gWDZZrl7/+Ug9NyH0VMiMhTpGYer0ijRiqHlTlqWKV0v1JIC7vY9kXtmC2Y ZFkgCxbe8m8M2S+uEV9VYd1697G2vLiV8/UjYCoLUlOFTXwKAcXgL6WivYLm8CaBVEBYk RiczSN0flK4ezAJLYaNcRInSVzyOD61UGzaNTvZQw/ZjuRpWI0K7PFZqO3NcvTGqENA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793717297; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=a8MklUW6PYR4NuTZFeyOULTC26VMv8Yp0HFaBobp5k0=; b=PYddg+ItX8mwghsuJGx5mFhr/cqDyImickYsJsMTa1xVx+agJ7D/olhfiLS15v+z5biO NgyUM+1rhHM5bIHcnQP8KS1zEIbGsTrboifir0prIphGBuM8NwBxeS70GROjWnUE9821q 9BBSSCXYrIIashaBE48dxUvk5iLUmkG0q80VVsZH6xD9sm0Q4P8ehDrSDW71xsj9FyTZ5 EkIBNJg1CGBtUnP8DBMLoD8SpDH6cxttCbLeUI7m/GKQlmj+YE+VKNrs488C4wAo9JoSt PQfXFEczOIPGR49x479a15grP8eoMZhaUObt97pg4CxPGFUFM1Gy2VtPwy6QyqiklXw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CTW1oFOr; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C9F3060A6F79; Tue, 3 Nov 2026 14:48:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CTW1oFOr Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A9DB1F00A1A; Tue, 3 Nov 2026 14:48:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793717296; bh=a8MklUW6PYR4NuTZFeyOULTC26VMv8Yp0HFaBobp5k0=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=CTW1oFOrdzEOUPkrvvNahWHPbA0e0ufZdo6mO+cLvubWXkN1/MNhM4qfQsKcdl+Fo 1UwmK1ZZSf+5SRMSnemcp5A+D5jWw7205V0qOh4ixmwKW9lcVMSnynlE0ubQ/VVFJi vxRny/8V9iZJ9ExkJe1Zb64JqIdngs34CEmUjkTlNHUYcB/2rTERNlv8IvRSCVxWkj 9ebpHdvYgFfFf7wQNgBo1bSmsBp+lLeElE2oJht2XJ26gE3MAd6LgY8lm3TBjwNy4G RseVsiRDCBb06aK2dHOLefpoLHMiBjl5dg1pKc3epjazs3c6zyNP5qcXlhjNXaq4bA 92C480cHTH15w== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC 24/38] proc/vmcore: don't let vmcore_cleanup() run twice at once Reply-To: sashiko-reviews@lists.linux.dev To: "Christian Brauner" Cc: "Linus Torvalds" , "Jann Horn" , "Josef Bacik" , "Chris Mason" , "Jeff Layton" , NeilBrown , "Eric Dumazet" , "Thomas Gleixner" , "Al Viro" , "Jonathan Corbet" , "Christoph Hellwig" , "Greg Kroah-Hartman" , "Joel Granados" , "Kees Cook" , "Jan Kara" , "Jan Kara" , linux-s390@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, linux-m68k@lists.linux-m68k.org, linux-serial@vger.kernel.org, "Takashi Iwai" , linux-ext4@vger.kernel.org, "Chuck Lever" , tytso@mit.edu, "Heiko Carstens" , "Vasily Gorbik" , "Alexander Gordeev" , "Christian Borntraeger" In-Reply-To: <20261102-work-procfs-bugfixes-v1-24-59422ed3e465@kernel.org> References: <20261102-work-procfs-bugfixes-v1-0-59422ed3e465@kernel.org> <20261102-work-procfs-bugfixes-v1-24-59422ed3e465@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 03 Nov 2026 14:48:14 +0000 X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > vmcore_cleanup() has a single caller, fadump's release_mem_store() on > powerpc. That checks fw_dump.dump_active without a lock and calls > vmcore_cleanup() without one, and kernfs only serializes the writers of > one open file. So two tasks that write to > /sys/kernel/fadump/release_mem through different files run > vmcore_cleanup() at the same time. >=20 > The first one removes /proc/vmcore and waits for its readers in > proc_remove(). The second one finds the entry already unlinked, returns > from proc_remove() right away and frees vmcore_list, the ELF headers > and the device dumps while those readers still walk them. Or both of > them free the same lists at once. >=20 > Serialize vmcore_cleanup() with a mutex of its own. It can't be > vmcore_mutex, removing /proc/vmcore calls release_vmcore() which takes > it. The second caller then finds nothing left to free. >=20 > Reported-by: Chris Mason > Fixes: b500afff11f6 ("fadump: Invalidate registration and release reserve= d memory for general use.") > Cc: stable@vger.kernel.org > Signed-off-by: Christian Brauner (Amutable) Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261102-work-procf= s-bugfixes-v1-0-59422ed3e465@kernel.org?part=3D24